of "this week." Tonight, our nation is in debt to the people of boston. Trail of terror. We're exhausted, folks, but we have a victory here tonight. A city resilient. We're strong. We're in it together. A country relieved. This morning, breaking details on the investigation. We remember the victims and we ask -- it is a tragedy. We are shocked. -- Who are the young men behind the carnage? It was a normal kid. He didn't really seem that he would harm a fly. What led these brothers to unspeakable violence? Could it have been prevented? We get to the heart of all of those questions right now. Good morning. What an extraordinary week it has been. Secretary of state kerry called it a direct confrontation with evil. Met with heroism and resolve. Now, so many questions about what motivated these marathon bombings and how america should confront the changing trend of terrorism? But let's get latest on the surviving suspect and on what comes next in the investigation from abc's senior correspondent pierre thomas in washington. Pierre, dzhokhar tsarnaev is in serious condition, and in no shape to be questioned. My sources are telling me that the suspect has a wound to the throat and neck area, that's made it very difficult to speak. He apparently knows police killed his brother, but that special interrogation team is standing by, ready to go. And they'll ask him questions at first without reading him his miranda rights. When do you expect charges to be filed? Charges could come as early today. Terror charges that could bring the death penalty. He won't be read his miranda rights. They're going to use the public safety can exception. They're taking this extraordinary stecause there could be an imminent threat still out there. I just got off the phone, george, with a senior law enforcement, of deep concern of ammunition, guns and working bombs these men had. They were so disciplined. Any indication of another sleeper cell? Right now, no evidence of a broader plot involving more people here, but law enforcement officials say they can't take that chance. The investigation is full tilt to find that out. Okay, pierre, thanks very

This transcript has been automatically generated and may not be 100% accurate.

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